Mechanical masking apparatus for producing a pattern on a curved surface

ABSTRACT

The invention relates to apparatus for masking selected portions of a curved surface to allow unit processing operations to be performed on the portions of the curved surface which are left exposed. In particular, the invention is a mechanical mask comprised of leaf-like projections having arcuate borders on the edges thereof. The arcuate borders are brought into engagement with a curved surface which is to have a processing operation performed thereon, thereby to mask that portion of the curved surface which is contacted by the arcuate borders of the leaflike projections.

United States Patent [1 1 Abita et al. A

MECHANICAL MASKING APPARATUS FOR 7 PRODUCING A PATTERN ON A CURVED SURFACE Inventors: Joseph L. Abita, Columbia; Carlton F. Noyes, Silver Spring, both of Md.

The United States of America as represented by the Secretary of the Navy, Washington, D.C.'

Filed: Apr. 9, 1973 Appl. No.: 349,160

Assignee:

U.S. Cl. 355/125, 355/133 Int. Cl. G03b 27/28 Field of Search 355/125, 126, 127, 133

References Cited. UNITED STATES PATENTS 12/1886 Butler ..'355/l25 X tions.

[45] Sept. 3, 1974 Primary ExaminerRichard M. Sheer The invention relates to apparatus for masking selected portionsof a curved surface to allow unit processing operations to be performed on the portions of the curved surface which are left exposed. In particu ABSTRACT lar, the invention is a mechanical mask comprised of leaf-like projections having arcuate borders on the "edges thereof. The arcuate borders are brought into engagement with a curved surface which is to have a processing operation performed thereon, thereby to mask that portion of the curved surface which is contacted by the arcuate borders of the leaf-like projec- 5 Claims, 4 Drawing Figures MECHANICAL MASKING APPARATUS FOR PRODUCING A PATTERN ON A CURVED SURFACE BACKGROUND ANDv SUMMARY OF THE INVENTION The present invention was conceived as a result of a need to produce a capacitive pattern on a curved surface. Techniques generally used for producing microelectronic circuits were not considered applicable to use with curved surfaces, such techniques being previously adaptable onlyto planar operations. However,

the present apparatus extends the use ofa variety of a holder having a notched spline 12 disposed in one end'thereof, the spline 12 receiving a flat plate 14 therein. The plate is mounted within the spline 12 by means of a set screw 16. That portion of the plate 14 which extends outwardlyfrom the holder 10 has a seriesof leaf-like projections extending therefrom. In the device shown, the projections comprise a triangular central leaf having lateral leaves 22 extending from either side thereof. The leaves 20 and 22 are formed with arcuate edges 23 defining arcuate border surfaces 24, which border surfaces have a finite width. The leaves 20 and 22 may be formed with enlarged base portions (not shown) to increase the structural strength The apparatus of the invention essentially comprises a support member having leaf-like projections extending from one end thereof. These leaf-like projections are configuredto provide a three-dimensional apparatus defining a pattern which is to be masked on a particular non-planar surface or object. In particular, the arcuate borders of the projections form masking surfaces which are brought into close-fitting contact with the surface to be masked. Those portions of the nonplanar surface being masked which are not contacted by these arcuate border surfacesare left exposed for a process ing operation to be performed thereon, the portion of the surface contacting the arcuate border surfaces being masked from the processing operation.

It is therefore a primary object of the invention to provide a mechanical apparatus for masking selected portions of a non-planar surface to allow processing operations to be performed on the exposed portions of said surface without affecting the portion thereof covered by the apparatus.

Further objects and advantages will become more readily apparent in light of the description of the preferred embodiments of the invention.

BRIEF DESCRIPTION OF. TI-IE'DRAWINGS' FIG. 1 is a perspective of a mechanical mask configured according to the invention;

FIG. 2 is a perspective illustrating attachment of a hemispherical device on which a capacitive pattern is to be formed to the mechanical mask of FIG. 1;

FIG. 3 is an elevation in partial section of the mechanical mask of the invention disposed in operative relation to the hemispherical device of FIG. 2 and held in engagement with the said device by means of a supporting yoke; and,

FIG. 4 is a top view of the hemispherical device illustrating the capacitive pattern formed thereon by use of the present mechanical mask.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention is seen in FIGS. 1 and 2 to comprise thereof.

In operation, the leaves 20 and 22 of the present device are brought into contact with a curved surface which has undergone a processing operation. such as metal or photoresist deposition. The particular device shown in FIG. 1 is intended to mask a concave portion of an internal hemispherical surface (as will be shown hereinafter) in order to produce a desired pattern thereon. The arcuate border surfaces 24 contact selected portions of the curved surface to mask those portions from the effects of the processing operation. The structure of the projections comprised of the leaves 20 and 22 could be altered to adapt to other curved or irregular shapes. For instance, the pattern provided bythe arcuate border surfaces 24 of the leaves 20 and 22 could be produced on the external surface of-a hemisphere by means of a convex arrangement of the leaves. Alternatively, the invention could be modified to produce patterns on the internal or external surfacesof cubes, rectangular solids, cones, or

any variety of regular or irregular surfaces by merely shaping the border surfaces 24 of the leaves accordingly.

.The masking pattern provided by the device of FIG. 1 is illustrated primarily due to its use in fabricating a capacitive pattern on an internal hemispherical surface which comprised a major structural portion of an aerospace experiment designed to measure drag on an orbiting satellite. Briefly, a hollow spherical housing having acapacitive pattern on the internal spherical surface was fabricated. The housing enclosed a small electrically conductive ball which, when the assembly is in earth orbit, has its own orbital parameters and is not subject to drag coefficients asis the main body of the carrier satellite. Therefore, when drag and friction losses change the orbital parameters of the carrier satellite withoutproducing a corresponding change in the orbital parameters of the enclosed ball, the capacitive relationship between the ball and the capacitive pattern on the internal surface of the enclosing sphere is altered. The information thus gained may be used in a variety of ways which are beyond the scope of this invention.

The significance of this invention lies in the provision of amasking apparatus which allows fabrication inter alia of a capacitive pattern on a non-planar surface such as the aforementioned spherical housing. FIG. 2 illustrates one hemisphere 30 of the spherical housing mentioned above prior to production of a capacitive pattern on the internalhemispherical surface thereof. As can be seen more clearly in FIG. 3, the internal surface of the hemisphere 30 has a layer 32 of chromium deposited thereon by a well-known sputtering technique. A layer 34 of photoresist material surmounts the deposited chromium layer 32. The photoresist layer 34 is cured with an infrared lamp prior to further processing. The photoresist material forming the layer 34 is best applied by placing the hemisphere 30 in a support cylinder (not shown) and spinning the assembly in a lathe while introducing the photoresist material into contact with the interior of the hemisphere with an eyedropper or other applicator.

As seen in both FIGS. 2 and 3, the device of FIG. 1 is mounted in the hemisphere 30 with the leaves 20 and 22 extending into the interior of the hemisphere to cause the arcuate border surfaces 24 to contact the layer 34 of photoresist material. The holder is mounted in a fixed relation tothe hemisphere 30 by means of a mounting device comprised of a cylindrical sleeve 38 mounted centrally on the bow of a U-shaped yoke 40, the arms of the yoke being attached to an annular plate 42. The holder 10 fits into the sleeve 38 and is locked therein by set screw 41. The annular plate 42 fits flush against a flange 44 surrounding the hemisphere 30, the plate 42 and flange 44 being held together by pins 46. The plate 42may effectively function as an additional masking element if it be desired that masking of the flange surfaces be accomplished.

Since selected surface portions of the photoresist layer 34 are masked by the contiguous surfaces of the arcuate border surfaces 24, unmasked portions of the photoresist layer 34 may be subjected to radiation from a mercury lamp to cause a change in polymer solubility in said unmasked portions of photoresist material. The masking apparatus may then be removed and the photoresist layer 34 developed with an appropriate photoresist developing solution to remove the photoresist material from the undeveloped portions of the layer 34, i.e., from those portions of the layer 34 masked by the arcuate borders 24 of the mechanical masking apparatus. The photoresist pattern required to protect certain portions of the chromium layer 32 during etching is thus generated. Portions of the chromium layer 32 not now covered by the photoresist layer 34 are then etched in a well-known fashion to remove chromium from those portions of thehemispherical surfacecorresponding to the pattern provided by the mechanical masking apparatus. A capacitive pattern is thus produced on the internal surface of the hemisphere 30 on removal of the remaining photoresist material, such as is shown in FIG. 4. The hemisphere 30 is seen to have discontinuous segments 50 of chromium disposed on the internal hemispherical surface, the lines of discontinuity 52 corresponding to the pattern formed by the arcuate border surfaces 24 defined by the arcuate edges 23 of the leaves 20 and 22.

Clearly, different patterns'could be formed on th curved hemispherical surface by an appropriate geometrical arrangement of the leaves 20 and 22. Simi? larly, the leaves 20 and 22 can be configured to provide border surfaces 24 which would positively contact and mask selected portions of virtually any non-planar surface. Accordingly, it will be, understood that the present apparatus may be configuredother than as is specifically shown and described, the scope and limits of the invention being defined according to the recitation of the appended claims.

We claim:

1. Apparatus for masking selected portions of a nonplanar surface on which a microelectronic processing operation is to be conducted, comprising:

.masking means having edges which conform to the perimetric shape of selected portions of the nonplanar surface which are to be masked;

said masking means having border surfaces lying between the aforesaid edges of said masking means, said border surfaces having a finite width and being engageable with the surfaces of the selected portions of the non-planar surface which are to be masked; thereby to mask the selected portions of said non-planar surface; and,

mounting means for fixedly holding the masking means in operative relation to said non-planar surface so that the border' surfaces of the masking means engage, contact, and thereby mask the surfaces of the selected portions of the non-planar surface.

2. The apparatus of claim 1 wherein the masking means comprise:

support means;

a triangular central leaf-like member extending from the support means; and,

lateral leaf-like members extending from either side of the central leaf, the leaf-like members terminating in edges conforming to the perimetric shape of selected portions of the non-planar surface which are to be masked, the border surfaces thereby defined by said edges forming at least a portion of the outer perimetric surfaces of the leaf-like members.

3. The apparatus of claim 2 wherein the support means comprises a shaft having a longitudinal axis, the triangular central leaf-like member extending from one end of the shaft, the body of the central leaf-like member lying in a plane parallel to the longitudinal axis of the shaft, and the planes in which the lateral leaf-like members lie being disposed atintersecting angles to the longitudinal axis of the shaft.

4. The apparatus of claim 3 wherein the mounting means comprise:

a sleeve for receiving said support means therein;

a-U-shaped yoke attached to one end of the sleeve at the base of the yoke, the yoke having arms extending from, said base;

a mounting plate attachedto the ends of the arms of said yoke, the plate being shaped to engage portions of the non planar surface;

means for attaching the mounting plate to the nonplanar surface whereby the leaf-like members extend beyond said mounting plate and into engagement with the non-planar surface to be masked; and,

means for fixedly securing said support means within said sleeve.

5. The apparatus of claim 3 wherein the edges of the leaf-like members are semi-circular in conformation. 

1. Apparatus for masking selected portions of a non-planar surface on which a microelectronic processing operation is to be conducted, comprising: masking means having edges which conform to the perimetric shape of selected portions of the non-planar surface which are to be masked; said masking means having border surfaces lying between the aforesaid edges of said masking means, said border surfaces having a finite width and being engageable with the surfaces of the selected portions of the non-planar surface which are to be masked, thereby to mask the selected portions of said nonplanar surface; and, mounting means for fixedly holding the masking means in operative relation to said non-planar surface so that the border surfaces of the masking means engage, contact, and thereby mask the surfaces of the selected portions of the nonplanar surface.
 2. The apparatus of claim 1 wherein the masking means comprise: support means; a triangular central leaf-like member extending from the support means; and, lateral leaf-like members extending from either side of the central leaf, the leaf-like members terminating in edges conforming to the perimetric shape of selected portions Of the non-planar surface which are to be masked, the border surfaces thereby defined by said edges forming at least a portion of the outer perimetric surfaces of the leaf-like members.
 3. The apparatus of claim 2 wherein the support means comprises a shaft having a longitudinal axis, the triangular central leaf-like member extending from one end of the shaft, the body of the central leaf-like member lying in a plane parallel to the longitudinal axis of the shaft, and the planes in which the lateral leaf-like members lie being disposed at intersecting angles to the longitudinal axis of the shaft.
 4. The apparatus of claim 3 wherein the mounting means comprise: a sleeve for receiving said support means therein; a U-shaped yoke attached to one end of the sleeve at the base of the yoke, the yoke having arms extending from said base; a mounting plate attached to the ends of the arms of said yoke, the plate being shaped to engage portions of the non planar surface; means for attaching the mounting plate to the non-planar surface whereby the leaf-like members extend beyond said mounting plate and into engagement with the non-planar surface to be masked; and, means for fixedly securing said support means within said sleeve.
 5. The apparatus of claim 3 wherein the edges of the leaf-like members are semi-circular in conformation. 